package com.rockbb.common.simpleframe.action;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.Serializable;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItem;
import org.apache.log4j.Logger;

public class CommonsMultipartFile implements MultipartFile, Serializable
{
	private static final long	serialVersionUID	= -2387403224137415279L;
	private static Logger logger = Logger.getLogger(CommonsMultipartFile.class);
	private final FileItem fileItem;
	private final long size;

	/**
	 * Create an instance wrapping the given FileItem.
	 * 
	 * @param fileItem
	 *            the FileItem to wrap
	 */
	protected CommonsMultipartFile(FileItem fileItem)
	{
		this.fileItem = fileItem;
		this.size = this.fileItem.getSize();
	}

	/**
	 * Return the underlying <code>org.apache.commons.fileupload.FileItem</code> instance. There is
	 * hardly any need to access this.
	 */
	public FileItem getFileItem()
	{
		return fileItem;
	}

	public String getName()
	{
		return this.fileItem.getFieldName();
	}

	public boolean isEmpty()
	{
		return (this.size == 0);
	}

	public String getOriginalFilename()
	{
		if (this.fileItem.getName() == null)
		{
			return null;
		}
		// check for Unix-style path
		int pos = this.fileItem.getName().lastIndexOf("/");
		if (pos == -1)
		{
			// check for Windows-style path
			pos = this.fileItem.getName().lastIndexOf("\\");
		}
		if (pos != -1)
		{
			// any sort of path separator found
			return this.fileItem.getName().substring(pos + 1);
		}
		else
		{
			// plain name
			return this.fileItem.getName();
		}
	}

	public String getContentType()
	{
		return this.fileItem.getContentType();
	}

	public long getSize()
	{
		return size;
	}

	public byte[] getBytes()
	{
		if (!isAvailable())
		{
			throw new IllegalStateException("File has been moved - cannot be read again");
		}
		byte[] bytes = this.fileItem.get();
		return (bytes != null ? bytes : new byte[0]);
	}

	public InputStream getInputStream() throws IOException
	{
		if (!isAvailable())
		{
			throw new IllegalStateException("File has been moved - cannot be read again");
		}
		InputStream inputStream = this.fileItem.getInputStream();
		return (inputStream != null ? inputStream : new ByteArrayInputStream(new byte[0]));
	}

	public void transferTo(File dest) throws IOException, IllegalStateException
	{
		if (!isAvailable())
		{
			throw new IllegalStateException(
					"File has already been moved - cannot be transferred again");
		}

		if (dest.exists() && !dest.delete())
		{
			throw new IOException("Destination file [" + dest.getAbsolutePath()
					+ "] already exists and could not be deleted");
		}

		try
		{
			this.fileItem.write(dest);
			if (logger.isDebugEnabled())
			{
				String action = "transferred";
				if (!this.fileItem.isInMemory())
				{
					action = isAvailable() ? "copied" : "moved";
				}
				logger.debug("Multipart file '" + getName() + "' with original filename ["
						+ getOriginalFilename() + "], stored " + getStorageDescription() + ": "
						+ action + " to [" + dest.getAbsolutePath() + "]");
			}
		}
		catch (FileUploadException ex)
		{
			throw new IllegalStateException(ex.getMessage());
		}
		catch (IOException ex)
		{
			throw ex;
		}
		catch (Exception ex)
		{
			logger.error("Could not transfer to file", ex);
			throw new IOException("Could not transfer to file: " + ex.getMessage());
		}
	}

	/**
	 * Determine whether the multipart content is still available. If a temporary file has been moved,
	 * the content is no longer available.
	 */
	protected boolean isAvailable()
	{
		// If in memory, it's available.
		if (this.fileItem.isInMemory())
		{
			return true;
		}
		// Check actual existence of temporary file.
		if (this.fileItem instanceof DiskFileItem)
		{
			return ((DiskFileItem) this.fileItem).getStoreLocation().exists();
		}
		// Check whether current file size is different than original one.
		return (this.fileItem.getSize() == this.size);
	}

	/**
	 * Return a description for the storage location of the multipart content. Tries to be as specific
	 * as possible: mentions the file location in case of a temporary file.
	 */
	protected String getStorageDescription()
	{
		if (this.fileItem.isInMemory())
		{
			return "in memory";
		}
		else if (this.fileItem instanceof DiskFileItem)
		{
			return "at [" + ((DiskFileItem) this.fileItem).getStoreLocation().getAbsolutePath()
					+ "]";
		}
		else
		{
			return "on disk";
		}
	}
}
